/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.sinosoft.monitor.org.objectweb.asm.util;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.sinosoft.monitor.org.objectweb.asm.AnnotationVisitor;
import com.sinosoft.monitor.org.objectweb.asm.Attribute;
import com.sinosoft.monitor.org.objectweb.asm.Handle;
import com.sinosoft.monitor.org.objectweb.asm.Label;
import com.sinosoft.monitor.org.objectweb.asm.MethodVisitor;
import com.sinosoft.monitor.org.objectweb.asm.Opcodes;
import com.sinosoft.monitor.org.objectweb.asm.Type;
import com.sinosoft.monitor.org.objectweb.asm.tree.MethodNode;
import com.sinosoft.monitor.org.objectweb.asm.tree.analysis.Analyzer;
import com.sinosoft.monitor.org.objectweb.asm.tree.analysis.BasicValue;
import com.sinosoft.monitor.org.objectweb.asm.tree.analysis.BasicVerifier;

/**
 * A {@link MethodVisitor} that checks that its methods are properly used. More
 * precisely this method adapter checks each instruction individually, i.e.,
 * each visit method checks some preconditions based <i>only</i> on its
 * arguments - such as the fact that the given opcode is correct for a given
 * visit method. This adapter can also perform some basic data flow checks (more
 * precisely those that can be performed without the full class hierarchy - see
 * {@link com.sinosoft.monitor.org.objectweb.asm.tree.analysis.BasicVerifier}). For instance in a
 * method whose signature is <tt>void m ()</tt>, the invalid instruction
 * IRETURN, or the invalid sequence IADD L2I will be detected if the data flow
 * checks are enabled. These checks are enabled by using the
 * {@link #CheckMethodAdapter(int, String, String, MethodVisitor, java.util.Map)} constructor.
 * They are not performed if any other constructor is used.
 *
 * @author Eric Bruneton
 */
public class CheckMethodAdapter extends MethodVisitor {

	/**
	 * The class version number.
	 */
	public int version;

	/**
	 * The access flags of the method.
	 */
	private int access;

	/**
	 * <tt>true</tt> if the visitCode method has been called.
	 */
	private boolean startCode;

	/**
	 * <tt>true</tt> if the visitMaxs method has been called.
	 */
	private boolean endCode;

	/**
	 * <tt>true</tt> if the visitEnd method has been called.
	 */
	private boolean endMethod;

	/**
	 * Number of visited instructions.
	 */
	private int insnCount;

	/**
	 * The already visited labels. This map associate Integer values to pseudo
	 * code offsets.
	 */
	private final Map<Label, Integer> labels;

	/**
	 * The labels used in this method. Every used label must be visited with
	 * visitLabel before the end of the method (i.e. should be in #labels).
	 */
	private Set<Label> usedLabels;

	/**
	 * Number of visited frames in expanded form.
	 */
	private int expandedFrames;

	/**
	 * Number of visited frames in compressed form.
	 */
	private int compressedFrames;

	/**
	 * Number of instructions before the last visited frame.
	 */
	private int lastFrame = -1;

	/**
	 * The exception handler ranges. Each pair of list element contains the
	 * start and end labels of an exception handler block.
	 */
	private List<Label> handlers;

	/**
	 * Code of the visit method to be used for each opcode.
	 */
	private static final int[] TYPE;

	/**
	 * The Label.status field.
	 */
	private static Field labelStatusField;

	static {
		String s = "BBBBBBBBBBBBBBBBCCIAADDDDDAAAAAAAAAAAAAAAAAAAABBBBBBBBDD"
				+ "DDDAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB"
				+ "BBBBBBBBBBBBBBBBBBBJBBBBBBBBBBBBBBBBBBBBHHHHHHHHHHHHHHHHD"
				+ "KLBBBBBBFFFFGGGGAECEBBEEBBAMHHAA";
		TYPE = new int[s.length()];
		for (int i = 0; i < TYPE.length; ++i) {
			TYPE[i] = s.charAt(i) - 'A' - 1;
		}
	}

	// code to generate the above string
	// public static void main (String[] args) {
	// int[] TYPE = new int[] {
	// 0, //NOP
	// 0, //ACONST_NULL
	// 0, //ICONST_M1
	// 0, //ICONST_0
	// 0, //ICONST_1
	// 0, //ICONST_2
	// 0, //ICONST_3
	// 0, //ICONST_4
	// 0, //ICONST_5
	// 0, //LCONST_0
	// 0, //LCONST_1
	// 0, //FCONST_0
	// 0, //FCONST_1
	// 0, //FCONST_2
	// 0, //DCONST_0
	// 0, //DCONST_1
	// 1, //BIPUSH
	// 1, //SIPUSH
	// 7, //LDC
	// -1, //LDC_W
	// -1, //LDC2_W
	// 2, //ILOAD
	// 2, //LLOAD
	// 2, //FLOAD
	// 2, //DLOAD
	// 2, //ALOAD
	// -1, //ILOAD_0
	// -1, //ILOAD_1
	// -1, //ILOAD_2
	// -1, //ILOAD_3
	// -1, //LLOAD_0
	// -1, //LLOAD_1
	// -1, //LLOAD_2
	// -1, //LLOAD_3
	// -1, //FLOAD_0
	// -1, //FLOAD_1
	// -1, //FLOAD_2
	// -1, //FLOAD_3
	// -1, //DLOAD_0
	// -1, //DLOAD_1
	// -1, //DLOAD_2
	// -1, //DLOAD_3
	// -1, //ALOAD_0
	// -1, //ALOAD_1
	// -1, //ALOAD_2
	// -1, //ALOAD_3
	// 0, //IALOAD
	// 0, //LALOAD
	// 0, //FALOAD
	// 0, //DALOAD
	// 0, //AALOAD
	// 0, //BALOAD
	// 0, //CALOAD
	// 0, //SALOAD
	// 2, //ISTORE
	// 2, //LSTORE
	// 2, //FSTORE
	// 2, //DSTORE
	// 2, //ASTORE
	// -1, //ISTORE_0
	// -1, //ISTORE_1
	// -1, //ISTORE_2
	// -1, //ISTORE_3
	// -1, //LSTORE_0
	// -1, //LSTORE_1
	// -1, //LSTORE_2
	// -1, //LSTORE_3
	// -1, //FSTORE_0
	// -1, //FSTORE_1
	// -1, //FSTORE_2
	// -1, //FSTORE_3
	// -1, //DSTORE_0
	// -1, //DSTORE_1
	// -1, //DSTORE_2
	// -1, //DSTORE_3
	// -1, //ASTORE_0
	// -1, //ASTORE_1
	// -1, //ASTORE_2
	// -1, //ASTORE_3
	// 0, //IASTORE
	// 0, //LASTORE
	// 0, //FASTORE
	// 0, //DASTORE
	// 0, //AASTORE
	// 0, //BASTORE
	// 0, //CASTORE
	// 0, //SASTORE
	// 0, //POP
	// 0, //POP2
	// 0, //DUP
	// 0, //DUP_X1
	// 0, //DUP_X2
	// 0, //DUP2
	// 0, //DUP2_X1
	// 0, //DUP2_X2
	// 0, //SWAP
	// 0, //IADD
	// 0, //LADD
	// 0, //FADD
	// 0, //DADD
	// 0, //ISUB
	// 0, //LSUB
	// 0, //FSUB
	// 0, //DSUB
	// 0, //IMUL
	// 0, //LMUL
	// 0, //FMUL
	// 0, //DMUL
	// 0, //IDIV
	// 0, //LDIV
	// 0, //FDIV
	// 0, //DDIV
	// 0, //IREM
	// 0, //LREM
	// 0, //FREM
	// 0, //DREM
	// 0, //INEG
	// 0, //LNEG
	// 0, //FNEG
	// 0, //DNEG
	// 0, //ISHL
	// 0, //LSHL
	// 0, //ISHR
	// 0, //LSHR
	// 0, //IUSHR
	// 0, //LUSHR
	// 0, //IAND
	// 0, //LAND
	// 0, //IOR
	// 0, //LOR
	// 0, //IXOR
	// 0, //LXOR
	// 8, //IINC
	// 0, //I2L
	// 0, //I2F
	// 0, //I2D
	// 0, //L2I
	// 0, //L2F
	// 0, //L2D
	// 0, //F2I
	// 0, //F2L
	// 0, //F2D
	// 0, //D2I
	// 0, //D2L
	// 0, //D2F
	// 0, //I2B
	// 0, //I2C
	// 0, //I2S
	// 0, //LCMP
	// 0, //FCMPL
	// 0, //FCMPG
	// 0, //DCMPL
	// 0, //DCMPG
	// 6, //IFEQ
	// 6, //IFNE
	// 6, //IFLT
	// 6, //IFGE
	// 6, //IFGT
	// 6, //IFLE
	// 6, //IF_ICMPEQ
	// 6, //IF_ICMPNE
	// 6, //IF_ICMPLT
	// 6, //IF_ICMPGE
	// 6, //IF_ICMPGT
	// 6, //IF_ICMPLE
	// 6, //IF_ACMPEQ
	// 6, //IF_ACMPNE
	// 6, //GOTO
	// 6, //JSR
	// 2, //RET
	// 9, //TABLESWITCH
	// 10, //LOOKUPSWITCH
	// 0, //IRETURN
	// 0, //LRETURN
	// 0, //FRETURN
	// 0, //DRETURN
	// 0, //ARETURN
	// 0, //RETURN
	// 4, //GETSTATIC
	// 4, //PUTSTATIC
	// 4, //GETFIELD
	// 4, //PUTFIELD
	// 5, //INVOKEVIRTUAL
	// 5, //INVOKESPECIAL
	// 5, //INVOKESTATIC
	// 5, //INVOKEINTERFACE
	// -1, //INVOKEDYNAMIC
	// 3, //NEW
	// 1, //NEWARRAY
	// 3, //ANEWARRAY
	// 0, //ARRAYLENGTH
	// 0, //ATHROW
	// 3, //CHECKCAST
	// 3, //INSTANCEOF
	// 0, //MONITORENTER
	// 0, //MONITOREXIT
	// -1, //WIDE
	// 11, //MULTIANEWARRAY
	// 6, //IFNULL
	// 6, //IFNONNULL
	// -1, //GOTO_W
	// -1 //JSR_W
	// };
	// for (int i = 0; i < TYPE.length; ++i) {
	// System.out.print((char)(TYPE[i] + 1 + 'A'));
	// }
	// System.out.println();
	// }

	/**
	 * Constructs a new {@link com.sinosoft.monitor.com.sinosoft.monitor.org.objectweb.asm.util.CheckMethodAdapter} object. This method adapter
	 * will not perform any data flow check (see
	 * {@link #CheckMethodAdapter(int, String, String, MethodVisitor, java.util.Map)}).
	 * <i>Subclasses must not use this constructor</i>. Instead, they must use
	 * the {@link #CheckMethodAdapter(int, MethodVisitor, java.util.Map)} version.
	 *
	 * @param mv the method visitor to which this adapter must delegate calls.
	 */
	public CheckMethodAdapter(final MethodVisitor mv) {
		this(mv, new HashMap<Label, Integer>());
	}

	/**
	 * Constructs a new {@link com.sinosoft.monitor.com.sinosoft.monitor.org.objectweb.asm.util.CheckMethodAdapter} object. This method adapter
	 * will not perform any data flow check (see
	 * {@link #CheckMethodAdapter(int, String, String, MethodVisitor, java.util.Map)}).
	 * <i>Subclasses must not use this constructor</i>. Instead, they must use
	 * the {@link #CheckMethodAdapter(int, MethodVisitor, java.util.Map)} version.
	 *
	 * @param mv     the method visitor to which this adapter must delegate calls.
	 * @param labels a map of already visited labels (in other methods).
	 */
	public CheckMethodAdapter(final MethodVisitor mv,
	                          final Map<Label, Integer> labels) {
		this(Opcodes.ASM4, mv, labels);
	}

	/**
	 * Constructs a new {@link com.sinosoft.monitor.com.sinosoft.monitor.org.objectweb.asm.util.CheckMethodAdapter} object. This method adapter
	 * will not perform any data flow check (see
	 * {@link #CheckMethodAdapter(int, String, String, MethodVisitor, java.util.Map)}).
	 *
	 * @param mv     the method visitor to which this adapter must delegate calls.
	 * @param labels a map of already visited labels (in other methods).
	 */
	protected CheckMethodAdapter(final int api, final MethodVisitor mv,
	                             final Map<Label, Integer> labels) {
		super(api, mv);
		this.labels = labels;
		this.usedLabels = new HashSet<Label>();
		this.handlers = new ArrayList<Label>();
	}

	/**
	 * Constructs a new {@link com.sinosoft.monitor.com.sinosoft.monitor.org.objectweb.asm.util.CheckMethodAdapter} object. This method adapter
	 * will perform basic data flow checks. For instance in a method whose
	 * signature is <tt>void m ()</tt>, the invalid instruction IRETURN, or the
	 * invalid sequence IADD L2I will be detected.
	 *
	 * @param access the method's access flags.
	 * @param name   the method's name.
	 * @param desc   the method's descriptor (see {@link Type Type}).
	 * @param cmv    the method visitor to which this adapter must delegate calls.
	 * @param labels a map of already visited labels (in other methods).
	 */
	public CheckMethodAdapter(final int access, final String name,
	                          final String desc, final MethodVisitor cmv,
	                          final Map<Label, Integer> labels) {
		this(new MethodNode(access, name, desc, null, null) {
			@Override
			public void visitEnd() {
				Analyzer<BasicValue> a = new Analyzer<BasicValue>(
						new BasicVerifier());
				try {
					a.analyze("dummy", this);
				} catch (Exception e) {
					if (e instanceof IndexOutOfBoundsException
							&& maxLocals == 0 && maxStack == 0) {
						throw new RuntimeException(
								"Data flow checking option requires valid, non zero maxLocals and maxStack values.");
					}
					e.printStackTrace();
					StringWriter sw = new StringWriter();
					PrintWriter pw = new PrintWriter(sw, true);
					CheckClassAdapter.printAnalyzerResult(this, a, pw);
					pw.close();
					throw new RuntimeException(e.getMessage() + ' '
							+ sw.toString());
				}
				accept(cmv);
			}
		}, labels);
		this.access = access;
	}

	@Override
	public AnnotationVisitor visitAnnotation(final String desc,
	                                         final boolean visible) {
		checkEndMethod();
		checkDesc(desc, false);
		return new CheckAnnotationAdapter(super.visitAnnotation(desc, visible));
	}

	@Override
	public AnnotationVisitor visitAnnotationDefault() {
		checkEndMethod();
		return new CheckAnnotationAdapter(super.visitAnnotationDefault(), false);
	}

	@Override
	public AnnotationVisitor visitParameterAnnotation(final int parameter,
	                                                  final String desc, final boolean visible) {
		checkEndMethod();
		checkDesc(desc, false);
		return new CheckAnnotationAdapter(super.visitParameterAnnotation(
				parameter, desc, visible));
	}

	@Override
	public void visitAttribute(final Attribute attr) {
		checkEndMethod();
		if (attr == null) {
			throw new IllegalArgumentException(
					"Invalid attribute (must not be null)");
		}
		super.visitAttribute(attr);
	}

	@Override
	public void visitCode() {
		System.out.println("visitCode...");
		if ((access & Opcodes.ACC_ABSTRACT) != 0) {
			throw new RuntimeException("Abstract methods cannot have code");
		}
		startCode = true;
		super.visitCode();
	}

	@Override
	public void visitFrame(final int type, final int nLocal,
	                       final Object[] local, final int nStack, final Object[] stack) {
		if (insnCount == lastFrame) {
			throw new IllegalStateException(
					"At most one frame can be visited at a given code location.");
		}
		lastFrame = insnCount;
		int mLocal;
		int mStack;
		switch (type) {
			case Opcodes.F_NEW:
			case Opcodes.F_FULL:
				mLocal = Integer.MAX_VALUE;
				mStack = Integer.MAX_VALUE;
				break;

			case Opcodes.F_SAME:
				mLocal = 0;
				mStack = 0;
				break;

			case Opcodes.F_SAME1:
				mLocal = 0;
				mStack = 1;
				break;

			case Opcodes.F_APPEND:
			case Opcodes.F_CHOP:
				mLocal = 3;
				mStack = 0;
				break;

			default:
				throw new IllegalArgumentException("Invalid frame type " + type);
		}

		if (nLocal > mLocal) {
			throw new IllegalArgumentException("Invalid nLocal=" + nLocal
					+ " for frame type " + type);
		}
		if (nStack > mStack) {
			throw new IllegalArgumentException("Invalid nStack=" + nStack
					+ " for frame type " + type);
		}

		if (type != Opcodes.F_CHOP) {
			if (nLocal > 0 && (local == null || local.length < nLocal)) {
				throw new IllegalArgumentException(
						"Array local[] is shorter than nLocal");
			}
			for (int i = 0; i < nLocal; ++i) {
				checkFrameValue(local[i]);
			}
		}
		if (nStack > 0 && (stack == null || stack.length < nStack)) {
			throw new IllegalArgumentException(
					"Array stack[] is shorter than nStack");
		}
		for (int i = 0; i < nStack; ++i) {
			checkFrameValue(stack[i]);
		}
		if (type == Opcodes.F_NEW) {
			++expandedFrames;
		} else {
			++compressedFrames;
		}
		if (expandedFrames > 0 && compressedFrames > 0) {
			throw new RuntimeException(
					"Expanded and compressed frames must not be mixed.");
		}
		super.visitFrame(type, nLocal, local, nStack, stack);
	}

	@Override
	public void visitInsn(final int opcode) {
		checkStartCode();
		checkEndCode();
		checkOpcode(opcode, 0);
		super.visitInsn(opcode);
		++insnCount;
	}

	@Override
	public void visitIntInsn(final int opcode, final int operand) {
		checkStartCode();
		checkEndCode();
		checkOpcode(opcode, 1);
		switch (opcode) {
			case Opcodes.BIPUSH:
				checkSignedByte(operand, "Invalid operand");
				break;
			case Opcodes.SIPUSH:
				checkSignedShort(operand, "Invalid operand");
				break;
			// case Constants.NEWARRAY:
			default:
				if (operand < Opcodes.T_BOOLEAN || operand > Opcodes.T_LONG) {
					throw new IllegalArgumentException(
							"Invalid operand (must be an array type code T_...): "
									+ operand);
				}
		}
		super.visitIntInsn(opcode, operand);
		++insnCount;
	}

	@Override
	public void visitVarInsn(final int opcode, final int var) {
		checkStartCode();
		checkEndCode();
		checkOpcode(opcode, 2);
		checkUnsignedShort(var, "Invalid variable index");
		super.visitVarInsn(opcode, var);
		++insnCount;
	}

	@Override
	public void visitTypeInsn(final int opcode, final String type) {
		checkStartCode();
		checkEndCode();
		checkOpcode(opcode, 3);
		checkInternalName(type, "type");
		if (opcode == Opcodes.NEW && type.charAt(0) == '[') {
			throw new IllegalArgumentException(
					"NEW cannot be used to create arrays: " + type);
		}
		super.visitTypeInsn(opcode, type);
		++insnCount;
	}

	@Override
	public void visitFieldInsn(final int opcode, final String owner,
	                           final String name, final String desc) {
		checkStartCode();
		checkEndCode();
		checkOpcode(opcode, 4);
		checkInternalName(owner, "owner");
		checkUnqualifiedName(version, name, "name");
		checkDesc(desc, false);
		super.visitFieldInsn(opcode, owner, name, desc);
		++insnCount;
	}

	@Override
	public void visitMethodInsn(final int opcode, final String owner,
	                            final String name, final String desc) {
		checkStartCode();
		checkEndCode();
		checkOpcode(opcode, 5);
		if (opcode != Opcodes.INVOKESPECIAL || !"<init>".equals(name)) {
			checkMethodIdentifier(version, name, "name");
		}
		checkInternalName(owner, "owner");
		checkMethodDesc(desc);
		super.visitMethodInsn(opcode, owner, name, desc);
		++insnCount;
	}

	@Override
	public void visitInvokeDynamicInsn(String name, String desc, Handle bsm,
	                                   Object... bsmArgs) {
		checkStartCode();
		checkEndCode();
		checkMethodIdentifier(version, name, "name");
		checkMethodDesc(desc);
		if (bsm.getTag() != Opcodes.H_INVOKESTATIC
				&& bsm.getTag() != Opcodes.H_NEWINVOKESPECIAL) {
			throw new IllegalArgumentException("invalid handle tag "
					+ bsm.getTag());
		}
		for (int i = 0; i < bsmArgs.length; i++) {
			checkLDCConstant(bsmArgs[i]);
		}
		super.visitInvokeDynamicInsn(name, desc, bsm, bsmArgs);
		++insnCount;
	}

	@Override
	public void visitJumpInsn(final int opcode, final Label label) {
		checkStartCode();
		checkEndCode();
		checkOpcode(opcode, 6);
		checkLabel(label, false, "label");
		checkNonDebugLabel(label);
		super.visitJumpInsn(opcode, label);
		usedLabels.add(label);
		++insnCount;
	}

	@Override
	public void visitLabel(final Label label) {
		checkStartCode();
		checkEndCode();
		checkLabel(label, false, "label");
		if (labels.get(label) != null) {
			throw new IllegalArgumentException("Already visited label");
		}
		labels.put(label, new Integer(insnCount));
		super.visitLabel(label);
	}

	@Override
	public void visitLdcInsn(final Object cst) {
		checkStartCode();
		checkEndCode();
		checkLDCConstant(cst);
		super.visitLdcInsn(cst);
		++insnCount;
	}

	@Override
	public void visitIincInsn(final int var, final int increment) {
		checkStartCode();
		checkEndCode();
		checkUnsignedShort(var, "Invalid variable index");
		checkSignedShort(increment, "Invalid increment");
		super.visitIincInsn(var, increment);
		++insnCount;
	}

	@Override
	public void visitTableSwitchInsn(final int min, final int max,
	                                 final Label dflt, final Label... labels) {
		checkStartCode();
		checkEndCode();
		if (max < min) {
			throw new IllegalArgumentException("Max = " + max
					+ " must be greater than or equal to min = " + min);
		}
		checkLabel(dflt, false, "default label");
		checkNonDebugLabel(dflt);
		if (labels == null || labels.length != max - min + 1) {
			throw new IllegalArgumentException(
					"There must be max - min + 1 labels");
		}
		for (int i = 0; i < labels.length; ++i) {
			checkLabel(labels[i], false, "label at index " + i);
			checkNonDebugLabel(labels[i]);
		}
		super.visitTableSwitchInsn(min, max, dflt, labels);
		for (int i = 0; i < labels.length; ++i) {
			usedLabels.add(labels[i]);
		}
		++insnCount;
	}

	@Override
	public void visitLookupSwitchInsn(final Label dflt, final int[] keys,
	                                  final Label[] labels) {
		checkEndCode();
		checkStartCode();
		checkLabel(dflt, false, "default label");
		checkNonDebugLabel(dflt);
		if (keys == null || labels == null || keys.length != labels.length) {
			throw new IllegalArgumentException(
					"There must be the same number of keys and labels");
		}
		for (int i = 0; i < labels.length; ++i) {
			checkLabel(labels[i], false, "label at index " + i);
			checkNonDebugLabel(labels[i]);
		}
		super.visitLookupSwitchInsn(dflt, keys, labels);
		usedLabels.add(dflt);
		for (int i = 0; i < labels.length; ++i) {
			usedLabels.add(labels[i]);
		}
		++insnCount;
	}

	@Override
	public void visitMultiANewArrayInsn(final String desc, final int dims) {
		checkStartCode();
		checkEndCode();
		checkDesc(desc, false);
		if (desc.charAt(0) != '[') {
			throw new IllegalArgumentException(
					"Invalid descriptor (must be an array type descriptor): "
							+ desc);
		}
		if (dims < 1) {
			throw new IllegalArgumentException(
					"Invalid dimensions (must be greater than 0): " + dims);
		}
		if (dims > desc.lastIndexOf('[') + 1) {
			throw new IllegalArgumentException(
					"Invalid dimensions (must not be greater than dims(desc)): "
							+ dims);
		}
		super.visitMultiANewArrayInsn(desc, dims);
		++insnCount;
	}

	@Override
	public void visitTryCatchBlock(final Label start, final Label end,
	                               final Label handler, final String type) {
		checkStartCode();
		checkEndCode();
		checkLabel(start, false, "start label");
		checkLabel(end, false, "end label");
		checkLabel(handler, false, "handler label");
		checkNonDebugLabel(start);
		checkNonDebugLabel(end);
		checkNonDebugLabel(handler);
		if (labels.get(start) != null || labels.get(end) != null
				|| labels.get(handler) != null) {
			throw new IllegalStateException(
					"Try catch blocks must be visited before their labels");
		}
		if (type != null) {
			checkInternalName(type, "type");
		}
		super.visitTryCatchBlock(start, end, handler, type);
		handlers.add(start);
		handlers.add(end);
	}

	@Override
	public void visitLocalVariable(final String name, final String desc,
	                               final String signature, final Label start, final Label end,
	                               final int index) {
		checkStartCode();
		checkEndCode();
		checkUnqualifiedName(version, name, "name");
		checkDesc(desc, false);
		checkLabel(start, true, "start label");
		checkLabel(end, true, "end label");
		checkUnsignedShort(index, "Invalid variable index");
		int s = labels.get(start).intValue();
		int e = labels.get(end).intValue();
		if (e < s) {
			throw new IllegalArgumentException(
					"Invalid start and end labels (end must be greater than start)");
		}
		super.visitLocalVariable(name, desc, signature, start, end, index);
	}

	@Override
	public void visitLineNumber(final int line, final Label start) {
		checkStartCode();
		checkEndCode();
		checkUnsignedShort(line, "Invalid line number");
		checkLabel(start, true, "start label");
		super.visitLineNumber(line, start);
	}

	@Override
	public void visitMaxs(final int maxStack, final int maxLocals) {
		checkStartCode();
		checkEndCode();
		endCode = true;
		for (Label l : usedLabels) {
			if (labels.get(l) == null) {
				throw new IllegalStateException("Undefined label used");
			}
		}
		for (int i = 0; i < handlers.size(); ) {
			Integer start = labels.get(handlers.get(i++));
			Integer end = labels.get(handlers.get(i++));
			if (start == null || end == null) {
				throw new IllegalStateException(
						"Undefined try catch block labels");
			}
			if (end.intValue() <= start.intValue()) {
				throw new IllegalStateException(
						"Emty try catch block handler range");
			}
		}
		checkUnsignedShort(maxStack, "Invalid max stack");
		checkUnsignedShort(maxLocals, "Invalid max locals");
		super.visitMaxs(maxStack, maxLocals);
	}

	@Override
	public void visitEnd() {
		System.out.println("visit end...");
		checkEndMethod();
		endMethod = true;
		super.visitEnd();
	}

	// -------------------------------------------------------------------------

	/**
	 * Checks that the visitCode method has been called.
	 */
	void checkStartCode() {
		if (!startCode) {
			throw new IllegalStateException(
					"Cannot visit instructions before visitCode has been called.");
		}
	}

	/**
	 * Checks that the visitMaxs method has not been called.
	 */
	void checkEndCode() {
		if (endCode) {
			throw new IllegalStateException(
					"Cannot visit instructions after visitMaxs has been called.");
		}
	}

	/**
	 * Checks that the visitEnd method has not been called.
	 */
	void checkEndMethod() {
		if (endMethod) {
			throw new IllegalStateException(
					"Cannot visit elements after visitEnd has been called.");
		}
	}

	/**
	 * Checks a stack frame value.
	 *
	 * @param value the value to be checked.
	 */
	void checkFrameValue(final Object value) {
		if (value == Opcodes.TOP || value == Opcodes.INTEGER
				|| value == Opcodes.FLOAT || value == Opcodes.LONG
				|| value == Opcodes.DOUBLE || value == Opcodes.NULL
				|| value == Opcodes.UNINITIALIZED_THIS) {
			return;
		}
		if (value instanceof String) {
			checkInternalName((String) value, "Invalid stack frame value");
			return;
		}
		if (!(value instanceof Label)) {
			throw new IllegalArgumentException("Invalid stack frame value: "
					+ value);
		} else {
			usedLabels.add((Label) value);
		}
	}

	/**
	 * Checks that the type of the given opcode is equal to the given type.
	 *
	 * @param opcode the opcode to be checked.
	 * @param type   the expected opcode type.
	 */
	static void checkOpcode(final int opcode, final int type) {
		if (opcode < 0 || opcode > 199 || TYPE[opcode] != type) {
			throw new IllegalArgumentException("Invalid opcode: " + opcode);
		}
	}

	/**
	 * Checks that the given value is a signed byte.
	 *
	 * @param value the value to be checked.
	 * @param msg   an message to be used in case of error.
	 */
	static void checkSignedByte(final int value, final String msg) {
		if (value < Byte.MIN_VALUE || value > Byte.MAX_VALUE) {
			throw new IllegalArgumentException(msg
					+ " (must be a signed byte): " + value);
		}
	}

	/**
	 * Checks that the given value is a signed short.
	 *
	 * @param value the value to be checked.
	 * @param msg   an message to be used in case of error.
	 */
	static void checkSignedShort(final int value, final String msg) {
		if (value < Short.MIN_VALUE || value > Short.MAX_VALUE) {
			throw new IllegalArgumentException(msg
					+ " (must be a signed short): " + value);
		}
	}

	/**
	 * Checks that the given value is an unsigned short.
	 *
	 * @param value the value to be checked.
	 * @param msg   an message to be used in case of error.
	 */
	static void checkUnsignedShort(final int value, final String msg) {
		if (value < 0 || value > 65535) {
			throw new IllegalArgumentException(msg
					+ " (must be an unsigned short): " + value);
		}
	}

	/**
	 * Checks that the given value is an {@link Integer}, a{@link Float}, a
	 * {@link Long}, a {@link Double} or a {@link String}.
	 *
	 * @param cst the value to be checked.
	 */
	static void checkConstant(final Object cst) {
		if (!(cst instanceof Integer) && !(cst instanceof Float)
				&& !(cst instanceof Long) && !(cst instanceof Double)
				&& !(cst instanceof String)) {
			throw new IllegalArgumentException("Invalid constant: " + cst);
		}
	}

	void checkLDCConstant(final Object cst) {
		if (cst instanceof Type) {
			int s = ((Type) cst).getSort();
			if (s != Type.OBJECT && s != Type.ARRAY && s != Type.METHOD) {
				throw new IllegalArgumentException("Illegal LDC constant value");
			}
			if (s != Type.METHOD && (version & 0xFFFF) < Opcodes.V1_5) {
				throw new IllegalArgumentException(
						"ldc of a constant class requires at least version 1.5");
			}
			if (s == Type.METHOD && (version & 0xFFFF) < Opcodes.V1_7) {
				throw new IllegalArgumentException(
						"ldc of a method type requires at least version 1.7");
			}
		} else if (cst instanceof Handle) {
			if ((version & 0xFFFF) < Opcodes.V1_7) {
				throw new IllegalArgumentException(
						"ldc of a handle requires at least version 1.7");
			}
			int tag = ((Handle) cst).getTag();
			if (tag < Opcodes.H_GETFIELD || tag > Opcodes.H_INVOKEINTERFACE) {
				throw new IllegalArgumentException("invalid handle tag " + tag);
			}
		} else {
			checkConstant(cst);
		}
	}

	/**
	 * Checks that the given string is a valid unqualified name.
	 *
	 * @param version the class version.
	 * @param name    the string to be checked.
	 * @param msg     a message to be used in case of error.
	 */
	static void checkUnqualifiedName(int version, final String name,
	                                 final String msg) {
		if ((version & 0xFFFF) < Opcodes.V1_5) {
			checkIdentifier(name, msg);
		} else {
			for (int i = 0; i < name.length(); ++i) {
				if (".;[/".indexOf(name.charAt(i)) != -1) {
					throw new IllegalArgumentException("Invalid " + msg
							+ " (must be a valid unqualified name): " + name);
				}
			}
		}
	}

	/**
	 * Checks that the given string is a valid Java identifier.
	 *
	 * @param name the string to be checked.
	 * @param msg  a message to be used in case of error.
	 */
	static void checkIdentifier(final String name, final String msg) {
		checkIdentifier(name, 0, -1, msg);
	}

	/**
	 * Checks that the given substring is a valid Java identifier.
	 *
	 * @param name  the string to be checked.
	 * @param start index of the first character of the identifier (inclusive).
	 * @param end   index of the last character of the identifier (exclusive). -1
	 *              is equivalent to <tt>name.length()</tt> if name is not
	 *              <tt>null</tt>.
	 * @param msg   a message to be used in case of error.
	 */
	static void checkIdentifier(final String name, final int start,
	                            final int end, final String msg) {
		if (name == null || (end == -1 ? name.length() <= start : end <= start)) {
			throw new IllegalArgumentException("Invalid " + msg
					+ " (must not be null or empty)");
		}
		if (!Character.isJavaIdentifierStart(name.charAt(start))) {
			throw new IllegalArgumentException("Invalid " + msg
					+ " (must be a valid Java identifier): " + name);
		}
		int max = end == -1 ? name.length() : end;
		for (int i = start + 1; i < max; ++i) {
			if (!Character.isJavaIdentifierPart(name.charAt(i))) {
				throw new IllegalArgumentException("Invalid " + msg
						+ " (must be a valid Java identifier): " + name);
			}
		}
	}

	/**
	 * Checks that the given string is a valid Java identifier.
	 *
	 * @param version the class version.
	 * @param name    the string to be checked.
	 * @param msg     a message to be used in case of error.
	 */
	static void checkMethodIdentifier(int version, final String name,
	                                  final String msg) {
		if (name == null || name.length() == 0) {
			throw new IllegalArgumentException("Invalid " + msg
					+ " (must not be null or empty)");
		}
		if ((version & 0xFFFF) >= Opcodes.V1_5) {
			for (int i = 0; i < name.length(); ++i) {
				if (".;[/<>".indexOf(name.charAt(i)) != -1) {
					throw new IllegalArgumentException("Invalid " + msg
							+ " (must be a valid unqualified name): " + name);
				}
			}
			return;
		}
		if (!Character.isJavaIdentifierStart(name.charAt(0))) {
			throw new IllegalArgumentException(
					"Invalid "
							+ msg
							+ " (must be a '<init>', '<clinit>' or a valid Java identifier): "
							+ name);
		}
		for (int i = 1; i < name.length(); ++i) {
			if (!Character.isJavaIdentifierPart(name.charAt(i))) {
				throw new IllegalArgumentException(
						"Invalid "
								+ msg
								+ " (must be '<init>' or '<clinit>' or a valid Java identifier): "
								+ name);
			}
		}
	}

	/**
	 * Checks that the given string is a valid internal class name.
	 *
	 * @param name the string to be checked.
	 * @param msg  a message to be used in case of error.
	 */
	static void checkInternalName(final String name, final String msg) {
		if (name == null || name.length() == 0) {
			throw new IllegalArgumentException("Invalid " + msg
					+ " (must not be null or empty)");
		}
		if (name.charAt(0) == '[') {
			checkDesc(name, false);
		} else {
			checkInternalName(name, 0, -1, msg);
		}
	}

	/**
	 * Checks that the given substring is a valid internal class name.
	 *
	 * @param name  the string to be checked.
	 * @param start index of the first character of the identifier (inclusive).
	 * @param end   index of the last character of the identifier (exclusive). -1
	 *              is equivalent to <tt>name.length()</tt> if name is not
	 *              <tt>null</tt>.
	 * @param msg   a message to be used in case of error.
	 */
	static void checkInternalName(final String name, final int start,
	                              final int end, final String msg) {
		int max = end == -1 ? name.length() : end;
		try {
			int begin = start;
			int slash;
			do {
				slash = name.indexOf('/', begin + 1);
				if (slash == -1 || slash > max) {
					slash = max;
				}
				checkIdentifier(name, begin, slash, null);
				begin = slash + 1;
			} while (slash != max);
		} catch (IllegalArgumentException _) {
			throw new IllegalArgumentException(
					"Invalid "
							+ msg
							+ " (must be a fully qualified class name in internal form): "
							+ name);
		}
	}

	/**
	 * Checks that the given string is a valid type descriptor.
	 *
	 * @param desc      the string to be checked.
	 * @param canBeVoid <tt>true</tt> if <tt>V</tt> can be considered valid.
	 */
	static void checkDesc(final String desc, final boolean canBeVoid) {
		int end = checkDesc(desc, 0, canBeVoid);
		if (end != desc.length()) {
			throw new IllegalArgumentException("Invalid descriptor: " + desc);
		}
	}

	/**
	 * Checks that a the given substring is a valid type descriptor.
	 *
	 * @param desc      the string to be checked.
	 * @param start     index of the first character of the identifier (inclusive).
	 * @param canBeVoid <tt>true</tt> if <tt>V</tt> can be considered valid.
	 * @return the index of the last character of the type decriptor, plus one.
	 */
	static int checkDesc(final String desc, final int start,
	                     final boolean canBeVoid) {
		if (desc == null || start >= desc.length()) {
			throw new IllegalArgumentException(
					"Invalid type descriptor (must not be null or empty)");
		}
		int index;
		switch (desc.charAt(start)) {
			case 'V':
				if (canBeVoid) {
					return start + 1;
				} else {
					throw new IllegalArgumentException("Invalid descriptor: "
							+ desc);
				}
			case 'Z':
			case 'C':
			case 'B':
			case 'S':
			case 'I':
			case 'F':
			case 'J':
			case 'D':
				return start + 1;
			case '[':
				index = start + 1;
				while (index < desc.length() && desc.charAt(index) == '[') {
					++index;
				}
				if (index < desc.length()) {
					return checkDesc(desc, index, false);
				} else {
					throw new IllegalArgumentException("Invalid descriptor: "
							+ desc);
				}
			case 'L':
				index = desc.indexOf(';', start);
				if (index == -1 || index - start < 2) {
					throw new IllegalArgumentException("Invalid descriptor: "
							+ desc);
				}
				try {
					checkInternalName(desc, start + 1, index, null);
				} catch (IllegalArgumentException _) {
					throw new IllegalArgumentException("Invalid descriptor: "
							+ desc);
				}
				return index + 1;
			default:
				throw new IllegalArgumentException("Invalid descriptor: " + desc);
		}
	}

	/**
	 * Checks that the given string is a valid method descriptor.
	 *
	 * @param desc the string to be checked.
	 */
	static void checkMethodDesc(final String desc) {
		if (desc == null || desc.length() == 0) {
			throw new IllegalArgumentException(
					"Invalid method descriptor (must not be null or empty)");
		}
		if (desc.charAt(0) != '(' || desc.length() < 3) {
			throw new IllegalArgumentException("Invalid descriptor: " + desc);
		}
		int start = 1;
		if (desc.charAt(start) != ')') {
			do {
				if (desc.charAt(start) == 'V') {
					throw new IllegalArgumentException("Invalid descriptor: "
							+ desc);
				}
				start = checkDesc(desc, start, false);
			} while (start < desc.length() && desc.charAt(start) != ')');
		}
		start = checkDesc(desc, start + 1, true);
		if (start != desc.length()) {
			throw new IllegalArgumentException("Invalid descriptor: " + desc);
		}
	}

	/**
	 * Checks that the given label is not null. This method can also check that
	 * the label has been visited.
	 *
	 * @param label        the label to be checked.
	 * @param checkVisited <tt>true</tt> to check that the label has been visited.
	 * @param msg          a message to be used in case of error.
	 */
	void checkLabel(final Label label, final boolean checkVisited,
	                final String msg) {
		if (label == null) {
			throw new IllegalArgumentException("Invalid " + msg
					+ " (must not be null)");
		}
		if (checkVisited && labels.get(label) == null) {
			throw new IllegalArgumentException("Invalid " + msg
					+ " (must be visited first)");
		}
	}

	/**
	 * Checks that the given label is not a label used only for debug purposes.
	 *
	 * @param label the label to be checked.
	 */
	private static void checkNonDebugLabel(final Label label) {
		Field f = getLabelStatusField();
		int status = 0;
		try {
			status = f == null ? 0 : ((Integer) f.get(label)).intValue();
		} catch (IllegalAccessException e) {
			throw new Error("Internal error");
		}
		if ((status & 0x01) != 0) {
			throw new IllegalArgumentException(
					"Labels used for debug info cannot be reused for control flow");
		}
	}

	/**
	 * Returns the Field object corresponding to the Label.status field.
	 *
	 * @return the Field object corresponding to the Label.status field.
	 */
	private static Field getLabelStatusField() {
		if (labelStatusField == null) {
			labelStatusField = getLabelField("a");
			if (labelStatusField == null) {
				labelStatusField = getLabelField("status");
			}
		}
		return labelStatusField;
	}

	/**
	 * Returns the field of the Label class whose name is given.
	 *
	 * @param name a field name.
	 * @return the field of the Label class whose name is given, or null.
	 */
	private static Field getLabelField(final String name) {
		try {
			Field f = Label.class.getDeclaredField(name);
			f.setAccessible(true);
			return f;
		} catch (NoSuchFieldException e) {
			return null;
		}
	}
}
